The present invention is directed to an expansion dowel made up of an expansion member radially widenable by an expansion element. The expansion member has a through bore and two axially extending first slots open at the leading end of the expansion member and two axially extending second slots closed at the opposite ends. The second slots are offset in the circumferential direction by 90.degree. relative to the first slots.
An expansion dowel is disclosed in DE-OS 3 917 498 and has two open and two closed axially extending slots located on both sides of a central bore. The closed ended slots are offset through 90.degree. with respect to the open ended slots and the slots are arranged one after the other. To anchor an expansion dowel of the above type, the expansion element is driven in the insertion direction into the central bore of the expansion member. Due to a smaller cross-section of the central bore in the region of the axially extending slots, a radially expansion of the expansion member takes place and, at the same time, there is a compaction of the material of the expansion member. When the expansion element is driven in, it tends to run off center in the region of the slots, so that the expansion element is located in the expansion member obliquely of the axial direction at the end of the driving operation. Accordingly, the slots in the known expansion member are arranged one after the other and offset 90.degree. relative to one another. This arrangement affords a centering of the expansion element in the expansion member.
Since the transition region between the slots cannot be widened radially, bracing of the expansion member within the central bore cannot be attained. Due to the high material compaction occurring when the expansion element is driven in, there is the danger that the leading end region of the expansion member, where the axially extending open ended slots are located, is torn off.